Hi,
If you want to do some measuring, get a box of factory shells, and go to the SAAMI website (http://www.saami.org if I recall) and download the spec sheet for both the ammunition and the chamber. That will show you what you want, and should answer mikld's question, too.
These will tell you the range of sizes for various measurements, clearances, tolerances, and such. Measure the factory ammo, measure your ammo. If they're both within range, measure the chamber (might want to do a cast--Brownell's has the material) and measure it. You may have a tolerance stacking problem where the ammo's just a touch out of spec on the large side, the chamber's a touch out on the small side, and the two worlds are "colliding" in your case.
Shouldn't be too hard to do except the chamber cast will take a bit of time.
As for crimp: I try to learn from the people who know what they're doing. In the case of ammo, they would be the ammo factories. I know it's popular to say you don't need a crimp on xxxx caliber ammo. That's one of those Interwebs "truisms" that may prove true in certain individual cases, but won't hold up across the board in the big picture. To the best of my knowledge, I've NEVER seen a factory round that isn't crimped. The factories load more ammo in an hour than most of us will in a long lifetime, so follow their lead. BTW, the factories generally use more steps than we do for a couple of operations, such as the crimp. This lends some credence to the "seat bullet, crimp separately" approach of the Lee Factory Crimp Die and whatever similar approach other die mfrs use.
You can even duplicate that process with a single seating/crimping die if you don't mind some readjustments along the way: first, adjust your die so the crimp section doesn't touch the case, and adjust the seating pin to seat the bullet where you want it. Now adjust that pin out to where it doesn't touch the bullet, and adjust the die body to provide the desired crimp. Takes longer than having a dedicated die for each step, but it's doable.
Good luck!
Rick C